1. Field of the Invention
The present invention relates to a magnetic rotation detector for magnetically detecting a rotation angle, a rotational direction or a rotation speed of a rotary member in various kinds of devices in automotive vehicles.
2. Description of the Prior Art
In Japanese Patent Laid-open Publication No. 4(1992)-370763, there has been proposed a magnetic rotation detector of the type which includes a set of magnetoresistance elements provided adjacent to a magnetized gear such that the resistance value of the magnetoresistance elements is converted into a voltage signal in accordance with rotation of the magnetized gear and that the value of the converted voltage signal is compared with a reference voltage to produce a series of pulse signals. In the magnetic rotation detector, however, the magnetoresistance elements are in the form of a bridge circuit since variation of the resistance value relative to variation of the magnetic field is small. Accordingly, the magnetic rotation detector is provided with at least three terminals such a source terminal, an earth terminal and an output terminal for producing the series of pulse signals. Due to small variation of the resistance value of the magnetoresistance elements, the rotation detector is further provided with various circuits such as an amplifier, a waveform shaper, etc. to apply an output of the magnetoresistance elements to an electric control apparatus placed in a remote position apart therefrom. In such an arrangement as described above, the magnetic rotation detector is provided with various circuits including a condenser for prevention of radiowave disturbance and is electromagnetically shielded. For these reasons, the magnetic rotation detector becomes costly.